Effects of methyl parathion on northern bobwhite survivability

The effects of methyl parathion on survivability of wild northern bobwhites (Colinus virginianus) were investigated from 1986 to 1988 near Tallahassee, Florida. In three field seasons, 197 bobwhites were administered 0, 2, 4 or 6 mg/kg methyl parathion in corn oil by oral intubation, released and monitored for 14 using radio telemetry. Bobwhites receiving 6 mg/kg methyl parathion had lower survival (P = 0.022) than control birds due to predation, not overt toxicity. There were no differences (P > 0.05) among treatment groups in activity, but methyl parathion may have influenced covey integrity. Birds that survived methyl parathion treatment had brain cholinesterase activities similar to those of control bobwhites. The results suggest that if bobwhites receive sufficiently high methyl parathion exposure in their natural habitats, then their susceptibility to predation may increase.